Method of concentrating liquids containing organic matter



n. D. PEEBLES. METHOD OF CONCENTRATING LIQUIDS CONTAINING ORGANICMATTER.

APPLICATION FILED OCT. 30,1918. 1,438,502, Patented Dec. 12, 1922.

I n aren tor Fax/(Id D. 2986165 cflii ornegs Patented Dec. 12, 1922.

1,438,502 PATENT QFFICE.

DAVID D. renews, or nunnm, oarrro'rmra, assrenoa T0 BAIR, PEEBLES &wear, or EUREKA, CALIFORNIA, A coranrnunsnrr oousrsrme or FRED s. earn,DAVID D. renews, ononon 'r. TOOBY, AND FRANK n. TOOBY.

METHOD OF CONCENTRATING LIQUIDS CONTAINING ORGANIC MATTER.

Application filed October 30, 1918. Serial No. 260,228.

To all whom it may concern:

Be it known that 1, DAVID D. Pnnenns, a citizen of the United States,residing at Eureka, in the county of Humboldt and State of California,have invented new and useful Improvement in Methods of ConcentratingLiquids Containing Organic Matter, of which the following is aspecification.

This invention relates to the dehydration, condensation andconcentration of liquids, and pertains especially to the concentrationof milk.

In practice it has been general to efiect concentration or dehydrationof milk commercially by the so-called vacuum pan sys tem to which thereare various objections including: the initial expense of installation;the tendency of the liquors foaming and priming and being carried overwith the vapor escaping from the pan, resulting in serious loss adhesionof the concentrated material to the heated surfaces of the pan, therebyresulting in scorching and injury besides otherwise detrimentallyaffecting the concentration; the need of special apparatus forhomogenizing the milk; the need of a pro-heater before the milk goesinto: the pan; the inflexibility of the process by reason of the fixedratio that temperature bears to vacuum; the practical necessity ofmaintaining a high temperature in the vacuum pan to prevent incubationof the bacteria, thereby breaking down the chemical constituents of theoriginalmilk; and finally the necessity of separate sterilizingapparatus at destructively high temperatures.

The object of the present invention is to overcome .th'e foregoingdifiiculties by a simple, practical cyclical process, in whichtheconcentration of the milk is carried to any desired degree withoutmaterial loss of the milk values by evaporation, and which process theheating, sterilizing, evaporation, condensation and re-circulation areessentially carried on at temperatures either above or below incubatingtemperatures, and at temperatures at Which the milk is not detrimentallyafi'ected. .Inshort, the practical embodiment of the process bringsabout a concentrated milk product in which bacterial growth has beendestroyed or arrested, the milk has longer keepingqualities and theproduct possessesthe original flavor of bacteria.

the natural milk, a desideratum which has hitherto not been possible byany known process.

Generally speaking, the invention comprehends essentially the continuousand successlve circulation of the milk through the heater and thenceinto and through an expanslon chamber, and then back into the heateruntil the desired degree of concentrat1on has been effected; maintainingthe temperature in the heater at such a point that the heat is raisedsufiiciently above the incubatlng temperature of the bacteria contamedin the milk, this temperature above which the bacteria will germinatebeing a temperature that is destructive to the bacteria; maintaining,this high temperature foronly a relatively brief period of time, so thatthe milk will not be detrimentally affected in its chemical or physicalconstituency but will acquire the desired heat head 'for the next step,which is: the delivery of the heated milk into the expansion chamberwherein is maintained a. sufficiently high vacuum to remove the moistureby explosive efi'ect sothat the moisture in the bacteria suddenlyexp-ands, thereby disrupting the The release of the milk into the vacuumchamber also immediately chills the milk, below the temperature at whichgermination of bacteria is promoted, or at least at which lowertemperature in the vacuum expansion chamber germination is greatlyretarded. The milk after passing through the vacuum chamberis shortlyreturned to the heater and raised to a relatively high temperatureagain, sothat at no period during the cycle does the milk remain at sucha temperature as permits material develop- I ment of the bacteria.

Before passing on to a description of the The object of heating the 5Qneaaeoa to efi'ect pasteurization. It is also desirous not to keep themilk at a temperature of from 100 F. to 135 F. for any considerablelength of time as at this temperature the degree of vacuum. Forinstance, a 26 inch vacuum has a relative temperature of approximately124 F.; a 28 inch vacuum has a relative temperature of approximately 100F.; and a 29 inch vacuum has a relative temperature of approximately 78F;

hence the higher the vacuum the lower the temperature it is possible tooperate under.

From the foregoing enunciated principles it will be obvious that in avacuum pan system most of the operations are carried on under idealtemperatures for bacteria germination.

In my system the milk is alternately heated, as will be seen, toapproximately 160 F., which is a pasteurizing temperature, and thencooled to the temperature of the vacuum under which the concentrator isoperating, so that any bacterial growth that is in the milk will nothave time to germinate before the milk again reaches a highertemperature and said bacterial growth is destroyed.

The drawing illustrates an apparatus such as has been used and is usedby me in the practice of my process.

A represents a suitable reservoir or tank in which the milk to betreated is first placed. 2 is a tubular heater through which vacuum pump7, which is connected by a pipe 8 near the top of the chamber 6 andabove the spray nozzle 5.

The chamber 6 is connected by a barometric column 9 with the reservoir Afor the re-delivery into the latter of the return liquid from chamber 6.10 is a separator positioned in the vacuum line 5 and having a returnconnection 11 backl into the barometric column 9 for re-delivery intothe system of any milk that may be carried by entrainment over from thevacuum chamber. The concentrated liquid from the evaporator, afterre-delivery into the tank A, is re-circulated through the system and thecycle is repeated until a suitable degree of conoentratlon and viscosityof the liquor under treatment is reached, when it is dischar ed from theline through the pipe 12. uch is, briefly, the cycle of operatlon.

In practice I, employ a heater of the tubular type, in which the milk iscirculated through the tubes and brought to the desired temperature;time, temperature and velocity being related and important factors inthis particular step of the proi'es's.

In the evaporating chamber the degree of vacuum and the manner in whichthe milk is sprayed into the evaporating chamber are likewise importantfactors. It is essential that the pre-heated milk be sprayed into theexpansion chamber in a downward direction or at least in a directioncounter to the flow of the vapors leaving the expansion at 8; the milkspray impinging against the sides of the expansion chamber thusrupturingwhatever bubbles may be formed 'and allowing the liquor to flow downwardalong the sides of the expansion chamber in a thin film. The surfacetension of the liquor prevents it being picked up by the vapors leavingit.

ile any suitable character of spray nozzle may be employed, I prefer touse a bell-shaped outer casing with a spring seated conical spreader.14; the spring 15 being tensloned so that the valve may open to admit athin conoidal film of milk and spray it within the chamber under thepressure of the milk current passing through the heater.

High velocity in the hewtezz-This is a very essential feature. Inpractice I main tain a velocity through the heater in excess of fourfeet per second for the purpose of preventing the milk from becomingscorched, increasing the efficiency of the heater and preventingencrustation of the tubes by milk deposit. With a smaller tube perhaps aslightly slowervelocity would be permitted. The temperature on the tubesin the heater varies from 212 F. to 230 F. The milk, however, passingthrough this heated zone is driven at such a velocity that it does notrise above 160 F., a suitable pasteurizing temperature.

Violent evaporation in the expansion chamber under heat head.'llhe rapidfall of temperature below the pasteurizing temperature of 160 F,(approximately) takes place in the expansion chamber apparently in theform of an explosion. This lower temperature in the expansion chamberwill .be the temperature of the vacuum-therein the lower temperatures ofthe vacuum there is a very rapid and violent expansion of the moistureWithin these organisms, exactly the same character of expansion asoccurs in the opening of a blow-off from a I boiler or even a boilerexplosion itself. It

, teurization,

is this rapid expansion of the moisture within the organisms whichdisrupts the latter, and once this is done they will not furthergerminate.

The velocity at which the milk is delivered to the heater is immaterial.It is very material, though, the ratio that velocity bears totemperature of the heater in passing through the heater, so that'themilk is intermittently affected and yet it is heated to a pasteurizingdegree, and also that the heat head is supplied for evaporation. Thepassage of the milk from its pasteurizing temperature to a zone oftemperature below the ideal germinating limits must be rapid so as notto give the bacteria any material chance to germinate in the transitionfrom the higher to the lower temperatures. In practice, the milk iscirculated through the apparatus over and over again until the: desireddegree of concentration is reached; the degree of the concentrationbeing limited only by the degree of viscosity capable of being handledby the pump.

It will'be manifest that by this process the milk at all times is keptthoroughly homogenized.

Having thus described my invention, what I claim and desire to secure byLetters Patent is- 1. The process of concentrating liquid containingorganic matter which consists of continuously and successivelycirculating the liquid through a heater and thenceinto an expansionchamber in which a high degree of vacuum is maintained, theratio of thevelocity of the liquid containing organic matter passing through theheater and the temperature in the heater being such that the liquidcontaining organicmatter is subjected only momentarily to a temperaturewhereby it absorbs sufiicient heat to efie'ct j vaporization and toeffect passpraying the heated liquid containing organic matter suddenlyand 'by' pressure into the expanslon chamber, with? subsequent drawingthe vapors and liquid containing organic matter separately from theexpans10n chamber without access of air, and recirculating the partiallyconcentrated liquid containing organic matter from the expanslon chamberthrough the heater and expansion chamber until the desired degree ofconcentration is obtained/ 2. The method of concentrating milk whichconsists in the continuous and successive circulation of the milkthrough a heater under pressure and an expansion. chamber closed againstaccess of surrounding air, the temperature of the milk being alternatelysuddenly raised in the heater above the temperature at which germinationof the active organisms within the milk takes place and suddenly reducedin the expansion chamber to a temperature below that at which suchgermination is active, and removing the vapors resulting from theexpansion of the water of the milk in the expansion chamber separatelyfrom the milk, whereby at each successive cycle a percentage ofdehydration is efi'ected, and the milk is condensed and made moresterile without altering its chemical composition.

3. The method of concentrating liquid containing 'organic matter whichconsists in repeatedly circulating the liquid containing the matter fromand to a source of supply, momentarily passing the liquid containingthe. material at each cycle of circulation through a-heater suflicientlyhot to raise the temperature of the liquid not to exceed approximately170 F. to momentarily give the liquid containing the organic matter thedesired heat, then quickly discharging the heated liquid containing theorganic matter in a vacuum chamber before the high temperaturedetrimentally affects the organic matter. 4. The method of concentratingliquid containing organic matter which consists in repeatedlycirculating the liquid containing the organic matter from and to asource of supply through a heater at approximately iour feet per second,maintaining the heater at a temperature to momentarily heat the liquidcontainingthe organic matter up to a temperature'not to exceedapproximately its pasteurizing temperature, then quickly passing theliquid containing the organic matter into an expansion chamber whereinis maintained a low enough vacuum to give explosive evaporation to' theliquid to reduce it considerably below its pasteurizing temperaturebefore the higher temperature to which the liquid containing the organicmatter-has been heated, has had time to efi'ect any deleterious changein the qualit' of the material being concentrated an separating thevapor from the condensed liquid.

5. ,The method of concentrating liquid t S 1 F I high temperaturedetrimentally affects the organic matter, removing the vapor from thevacuum chamber through one conduit. and conducting the concentrated 1iuid con- 15 taining the organic matter. throng a different conduit tothe original source of supply and repeating the operation untilthedesired concentration-is efi'ected.

In testimony whereof I have hereunto set my hand in the presenceof twosubscribing witnesses.

- DAVID D. PEEBLES'.

Witnesses:

JOHN H, HERRING, W. W. HEALEY.

